[ERROR] : Group 'arm' is not a chain

asked 2021-04-06 05:50:26 -0500

fekix9 gravatar image

updated 2021-04-13 01:55:17 -0500

fvd gravatar image

Cross-posted on Github here.

I am a beginner in ROS. I wrote an urdf file and generated demo.launch with moveit setup assisient. When I roslaunch it, the following error occurred:

[ERROR] [1617752615.735037382]: Group 'arm' is not a chain

[ERROR] [1617752615.735223971]: Kinematics solver of type 'kdl_kinematics_plugin/KDLKinematicsPlugin' could not be initialized for group 'arm'

[ERROR] [1617752615.735414230]: Kinematics solver could not be instantiated for joint group arm.

[ WARN] [1617752615.850870497]: The root link base_link has an inertia specified in the URDF, but KDL does not support a root link with an inertia. As a workaround, you can add an extra dummy link to your URDF.

[ERROR] [1617752616.291773005]: Client [/move_group] wants topic /move_group/goal to have datatype/md5sum [moveit_msgs/MoveGroupActionGoal/689f0d7213d5960a2a9e9b117a0fdb73], but our version has [moveit_msgs/MoveGroupActionGoal/6514728724a6f4ce3f2f5a26db255bc9]. Dropping connection.

[ERROR] [1617752645.935486956]: Unable to connect to move_group action server 'move_group' within allotted time (30s)


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Please add the error message to the body of your question and fix the title.

fvd gravatar image fvd  ( 2021-04-06 09:27:43 -0500 )edit

I'm going to guess it's "group 'arm' is not a chain".

gvdhoorn gravatar image gvdhoorn  ( 2021-04-06 13:42:22 -0500 )edit

Yes,but I'm afraid I can't upload my urdf and srdf because I have no 5 points

fekix9 gravatar image fekix9  ( 2021-04-06 19:06:36 -0500 )edit

You do now, but it looks like you need to clean your workspace and check why your arm is not a chain. Most likely you included multiple fingers of a gripper.

fvd gravatar image fvd  ( 2021-04-06 20:03:36 -0500 )edit

It's not working.My urdf and srdf are here.

fekix9 gravatar image fekix9  ( 2021-04-06 23:57:44 -0500 )edit

Anyone can help me?

fekix9 gravatar image fekix9  ( 2021-04-08 07:36:30 -0500 )edit

Did you try removing the inertia from the base link and fixing the other errors? It seems like your versions don't match or you are building parts of moveit from source but not others. I don't see anything obviously wrong in the SRDF/URDF, but a picture would help. I might also try removing the gripper chain and end effector from the SRDF for debugging.

fvd gravatar image fvd  ( 2021-04-08 07:46:53 -0500 )edit

Thanks for your help!

fekix9 gravatar image fekix9  ( 2021-04-08 08:15:56 -0500 )edit